From The University of Arizona via : “New ultra-faint dwarf galaxy discovered” 

From The University of Arizona


May 26, 2022
Tomasz Nowakowski

Tucana B as seen in the DESI Legacy Imaging Surveys sky browser (left) and in the deeper Magellan r-band IMACS data (right), where it is more clearly resolved into stars. Credit: Sand et al., 2022.

Astronomers from the University of Arizona (UA) and elsewhere report the discovery of a new ultra-faint dwarf galaxy. The newfound galaxy, designated Tucana B, is the first quenched and isolated object of this type identified in the extreme outskirts of the Local Group. The finding is reported in a paper presented May 18, 2022 for The Astrophysical Letters.

The so-called ultra-faint dwarf galaxies (UFDs) are the least luminous, most dark-matter-dominated, and least chemically evolved galaxies known. Therefore, they are perceived by astronomers as the best candidate fossils from the universe at its early stages.

Now, a team of researchers led by UA’s David J. Sand has found a new UFD during a visual search for faint dwarf galaxy companions to the distant dwarf spheroidal galaxy Tucana. They used data from the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys Data Release 9 and their interactive color image viewer.

“We uploaded a custom file to mark off a region with a projected radius of 100 kpc (≈6.4 deg at the distance of Tucana) and searched for visual over-densities of resolved stars with underlying diffuse light, indicative of a dwarf galaxy at the edge of the Local Group. The field was inspected at a variety of spatial scales and contrast levels. Tucana B stood out during the search, and is partially resolved into stars in the Legacy Imaging Survey viewer,” the astronomers explained.

According to the paper, Tucana B is located about 6 degrees from the Tucana dwarf spheroidal, and is about 1.6 million light years more distant along the line of sight. The distance to Tucana B from the Earth was calculated to be approximately 4.5 million light years.

Tucana B has a half-light radius of some 260 light years, and an absolute magnitude of −6.9 mag, what makes it comparable to the ultra-faint satellite galaxies of the Milky Way. The UFD appears to only consist of an old metal-poor stellar population.

The astronomers noted that the luminosity of Tucana B and apparent lack of star formation and also neutral gas make it unique among recent discoveries at this approximate distance. Moreover, the extreme isolation of Tucana B may indicate that its star formation was quenched by reionization or some other internal mechanism, rather than interaction with a larger galaxy halo.

Sand’s team sees Tucana B as a great target for future space-based follow-up observations aiming to pin down its structure and star formation history, possibly down to the oldest main sequence turnoff.

“In particular, Tucana B may provide a definitive opportunity to understand the role that reionization plays in the quenching of the faintest galaxies,” the researchers concluded.

They added that finding more objects like Tucana B is necessary in order to better understand the demographics of the field UFD population.

See the full article here .

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As of 2019, the The University of Arizona enrolled 45,918 students in 19 separate colleges/schools, including The University of Arizona College of Medicine in Tucson and Phoenix and the James E. Rogers College of Law, and is affiliated with two academic medical centers (Banner – University Medical Center Tucson and Banner – University Medical Center Phoenix). The University of Arizona is one of three universities governed by the Arizona Board of Regents. The university is part of the Association of American Universities and is the only member from Arizona, and also part of the Universities Research Association . The university is classified among “R1: Doctoral Universities – Very High Research Activity”.

Known as the Arizona Wildcats (often shortened to “Cats”), The University of Arizona’s intercollegiate athletic teams are members of the Pac-12 Conference of the NCAA. The University of Arizona athletes have won national titles in several sports, most notably men’s basketball, baseball, and softball. The official colors of the university and its athletic teams are cardinal red and navy blue.

After the passage of the Morrill Land-Grant Act of 1862, the push for a university in Arizona grew. The Arizona Territory’s “Thieving Thirteenth” Legislature approved The University of Arizona in 1885 and selected the city of Tucson to receive the appropriation to build the university. Tucson hoped to receive the appropriation for the territory’s mental hospital, which carried a $100,000 allocation instead of the $25,000 allotted to the territory’s only university Arizona State University was also chartered in 1885, but it was created as Arizona’s normal school, and not a university). Flooding on the Salt River delayed Tucson’s legislators, and by the time they reached Prescott, back-room deals allocating the most desirable territorial institutions had been made. Tucson was largely disappointed with receiving what was viewed as an inferior prize.

With no parties willing to provide land for the new institution, the citizens of Tucson prepared to return the money to the Territorial Legislature until two gamblers and a saloon keeper decided to donate the land to build the school. Construction of Old Main, the first building on campus, began on October 27, 1887, and classes met for the first time in 1891 with 32 students in Old Main, which is still in use today. Because there were no high schools in Arizona Territory, the university maintained separate preparatory classes for the first 23 years of operation.


The University of Arizona is classified among “R1: Doctoral Universities – Very high research activity”. UArizona is the fourth most awarded public university by National Aeronautics and Space Administration for research. The University of Arizona was awarded over $325 million for its Lunar and Planetary Laboratory (LPL) to lead NASA’s 2007–08 mission to Mars to explore the Martian Arctic, and $800 million for its OSIRIS-REx mission, the first in U.S. history to sample an asteroid.

National Aeronautics Space Agency OSIRIS-REx Spacecraft.

The LPL’s work in the Cassini spacecraft orbit around Saturn is larger than any other university globally.

National Aeronautics and Space Administration/European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganisation](EU)/ASI Italian Space Agency [Agenzia Spaziale Italiana](IT) Cassini Spacecraft.

The University of Arizona laboratory designed and operated the atmospheric radiation investigations and imaging on the probe. The University of Arizona operates the HiRISE camera, a part of the Mars Reconnaissance Orbiter.

U Arizona NASA Mars Reconnaisance HiRISE Camera.

NASA Mars Reconnaissance Orbiter.

While using the HiRISE camera in 2011, University of Arizona alumnus Lujendra Ojha and his team discovered proof of liquid water on the surface of Mars—a discovery confirmed by NASA in 2015. The University of Arizona receives more NASA grants annually than the next nine top NASA/JPL-Caltech-funded universities combined. As of March 2016, The University of Arizona’s Lunar and Planetary Laboratory is actively involved in ten spacecraft missions: Cassini VIMS; Grail; the HiRISE camera orbiting Mars; the Juno mission orbiting Jupiter; Lunar Reconnaissance Orbiter (LRO); Maven, which will explore Mars’ upper atmosphere and interactions with the sun; Solar Probe Plus, a historic mission into the Sun’s atmosphere for the first time; Rosetta’s VIRTIS; WISE; and OSIRIS-REx, the first U.S. sample-return mission to a near-earth asteroid, which launched on September 8, 2016.

NASA – GRAIL Flying in Formation (Artist’s Concept). Credit: NASA.
National Aeronautics Space Agency Juno at Jupiter.

NASA/Lunar Reconnaissance Orbiter.


NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker. The Johns Hopkins University Applied Physics Lab.
National Aeronautics and Space Administration Wise/NEOWISE Telescope.

The University of Arizona students have been selected as Truman, Rhodes, Goldwater, and Fulbright Scholars. According to The Chronicle of Higher Education, UArizona is among the top 25 producers of Fulbright awards in the U.S.

The University of Arizona is a member of the Association of Universities for Research in Astronomy , a consortium of institutions pursuing research in astronomy. The association operates observatories and telescopes, notably Kitt Peak National Observatory just outside Tucson.

National Science Foundation NOIRLab National Optical Astronomy Observatory Kitt Peak National Observatory on Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers (55 mi) west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft). annotated.

Led by Roger Angel, researchers in the Steward Observatory Mirror Lab at The University of Arizona are working in concert to build the world’s most advanced telescope. Known as the Giant Magellan Telescope (CL), it will produce images 10 times sharper than those from the Earth-orbiting Hubble Telescope.

GMT Giant Magellan Telescope(CL) 21 meters, to be at the Carnegie Institution for Science’s NOIRLab NOAO Las Campanas Observatory(CL), some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high.

The telescope is set to be completed in 2021. GMT will ultimately cost $1 billion. Researchers from at least nine institutions are working to secure the funding for the project. The telescope will include seven 18-ton mirrors capable of providing clear images of volcanoes and riverbeds on Mars and mountains on the moon at a rate 40 times faster than the world’s current large telescopes. The mirrors of the Giant Magellan Telescope will be built at The University of Arizona and transported to a permanent mountaintop site in the Chilean Andes where the telescope will be constructed.

Reaching Mars in March 2006, the Mars Reconnaissance Orbiter contained the HiRISE camera, with Principal Investigator Alfred McEwen as the lead on the project. This National Aeronautics and Space Agency mission to Mars carrying the UArizona-designed camera is capturing the highest-resolution images of the planet ever seen. The journey of the orbiter was 300 million miles. In August 2007, The University of Arizona, under the charge of Scientist Peter Smith, led the Phoenix Mars Mission, the first mission completely controlled by a university. Reaching the planet’s surface in May 2008, the mission’s purpose was to improve knowledge of the Martian Arctic. The Arizona Radio Observatory , a part of The University of Arizona Department of Astronomy Steward Observatory , operates the Submillimeter Telescope on Mount Graham.

University of Arizona Radio Observatory at NOAO Kitt Peak National Observatory, AZ USA, U Arizona Department of Astronomy and Steward Observatory at altitude 2,096 m (6,877 ft).

Kitt Peak National Observatory in the Arizona-Sonoran Desert 88 kilometers 55 mi west-southwest of Tucson, Arizona in the Quinlan Mountains of the Tohono O’odham Nation, altitude 2,096 m (6,877 ft)

The National Science Foundation funded the iPlant Collaborative in 2008 with a $50 million grant. In 2013, iPlant Collaborative received a $50 million renewal grant. Rebranded in late 2015 as “CyVerse”, the collaborative cloud-based data management platform is moving beyond life sciences to provide cloud-computing access across all scientific disciplines.

In June 2011, the university announced it would assume full ownership of the Biosphere 2 scientific research facility in Oracle, Arizona, north of Tucson, effective July 1. Biosphere 2 was constructed by private developers (funded mainly by Texas businessman and philanthropist Ed Bass) with its first closed system experiment commencing in 1991. The university had been the official management partner of the facility for research purposes since 2007.

U Arizona mirror lab-Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

University of Arizona’s Biosphere 2, located in the Sonoran desert. An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why The University of Arizona is a university unlike any other.

University of Arizona Landscape Evolution Observatory at Biosphere 2.